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Questions and Answers
Which step is not involved in viral pathogenesis?
Which step is not involved in viral pathogenesis?
- Entry and primary replication
- Host immune response
- Cellular injury
- Viral mutation (correct)
What does viral shedding pertain to in viral pathogenesis?
What does viral shedding pertain to in viral pathogenesis?
- Viral entry into host cells
- Viral spread within the host
- Host immune response to viral infection
- Shedding of infectious virus into the environment (correct)
What does it mean if a strain of a virus is more virulent than another strain?
What does it mean if a strain of a virus is more virulent than another strain?
- It has a higher rate of mutation
- It commonly produces more severe disease in a susceptible host (correct)
- It has a longer incubation period
- It spreads faster within the host
What is the difference between viral virulence in intact animals and cytopathogenicity for cultured cells?
What is the difference between viral virulence in intact animals and cytopathogenicity for cultured cells?
When does viral shedding usually occur in viral pathogenesis?
When does viral shedding usually occur in viral pathogenesis?
Which of the following is NOT a virus-encoded mechanism for modulation of NK cell activity?
Which of the following is NOT a virus-encoded mechanism for modulation of NK cell activity?
Which pathway does NOT activate the complement system?
Which pathway does NOT activate the complement system?
What is the main focus of B lymphocytes in the immune response?
What is the main focus of B lymphocytes in the immune response?
What is the role of T lymphocytes in cell-mediated immunity?
What is the role of T lymphocytes in cell-mediated immunity?
Which cells have inhibitory and activating receptors to monitor the presence of viral infection?
Which cells have inhibitory and activating receptors to monitor the presence of viral infection?
What is the process that occurs when interferons are released and bind to IFNAR receptors?
What is the process that occurs when interferons are released and bind to IFNAR receptors?
Which type of IFNs induce local signaling system and help to establish antiviral response?
Which type of IFNs induce local signaling system and help to establish antiviral response?
What is the role of 2’,5’-oligo A synthetase activated by dsRNA?
What is the role of 2’,5’-oligo A synthetase activated by dsRNA?
What is the effect of the inflammatory cytokines IL-1, IL-6, TNF-α in response to viral infection?
What is the effect of the inflammatory cytokines IL-1, IL-6, TNF-α in response to viral infection?
Which proteins are part of the innate immune response and activate the adaptive immune response?
Which proteins are part of the innate immune response and activate the adaptive immune response?
Which type of infection occurs when a virus crosses the placenta during pregnancy?
Which type of infection occurs when a virus crosses the placenta during pregnancy?
What is the main route for viral spread in the body?
What is the main route for viral spread in the body?
Which type of cells can be used by the virus to enter organs through transcytosis?
Which type of cells can be used by the virus to enter organs through transcytosis?
What determines the pattern of systemic illness during a viral infection?
What determines the pattern of systemic illness during a viral infection?
How do viruses like HPV access the body?
How do viruses like HPV access the body?
Which type of immune response does the host's recognition of Toll-like receptors (TLRs) and NOD-like receptors (NLRs) activate?
Which type of immune response does the host's recognition of Toll-like receptors (TLRs) and NOD-like receptors (NLRs) activate?
What is the function of cytoplasmic RNA helicase MDA5 in the host immune response to viral infections?
What is the function of cytoplasmic RNA helicase MDA5 in the host immune response to viral infections?
How does the rabies virus evade the immune response and enter the blood-brain barrier (BBB)?
How does the rabies virus evade the immune response and enter the blood-brain barrier (BBB)?
What type of viral spread occurs through lytic and lysogenic responses during replication?
What type of viral spread occurs through lytic and lysogenic responses during replication?
What is the role of protein kinase R (PKR) in the host immune response to viral infections?
What is the role of protein kinase R (PKR) in the host immune response to viral infections?
Which type of transmission involves the transmission of virions in respiratory droplets?
Which type of transmission involves the transmission of virions in respiratory droplets?
Which part of the body is the most common portal of entry for viruses into the human body?
Which part of the body is the most common portal of entry for viruses into the human body?
Which type of cells are less abundant in the lower respiratory tract compared to the upper respiratory tract?
Which type of cells are less abundant in the lower respiratory tract compared to the upper respiratory tract?
Which specialized cells play roles in immune surveillance and defense in the gastrointestinal tract?
Which specialized cells play roles in immune surveillance and defense in the gastrointestinal tract?
Which type of viruses contain capsid proteins that are not denatured by low pH?
Which type of viruses contain capsid proteins that are not denatured by low pH?
What is the term for the time at which an infected individual is infectious to contacts?
What is the term for the time at which an infected individual is infectious to contacts?
Which term refers to a virus being pathogenic for a particular host if it can infect and cause signs of disease in that host?
Which term refers to a virus being pathogenic for a particular host if it can infect and cause signs of disease in that host?
What does the term 'cytopathogenicity' for cultured cells refer to?
What does the term 'cytopathogenicity' for cultured cells refer to?
Which step in viral pathogenesis involves the entry and primary replication of the virus?
Which step in viral pathogenesis involves the entry and primary replication of the virus?
What is the term for the last stage in viral pathogenesis, representing the time at which an infected individual is infectious to contacts?
What is the term for the last stage in viral pathogenesis, representing the time at which an infected individual is infectious to contacts?
Which enzyme dephosphorylates the Phosphate group of specific MAMPS recognized by the card domain?
Which enzyme dephosphorylates the Phosphate group of specific MAMPS recognized by the card domain?
What is the role of TRIM25 and Riplet in the ubiquitination process of CARD domains?
What is the role of TRIM25 and Riplet in the ubiquitination process of CARD domains?
What is the function of MAVS in the context of ubiquitinated CARD domains?
What is the function of MAVS in the context of ubiquitinated CARD domains?
What is the consequence of IKK homodimerization and phosphorylation of IKB?
What is the consequence of IKK homodimerization and phosphorylation of IKB?
What activates the IRF by phosphorylating and stabilizing them?
What activates the IRF by phosphorylating and stabilizing them?
Which pathway does NOT activate the complement system?
Which pathway does NOT activate the complement system?
Which type of cells mediate humoral immunity in the immune response?
Which type of cells mediate humoral immunity in the immune response?
What is the role of MHC I on a normal cell in relation to NK cells?
What is the role of MHC I on a normal cell in relation to NK cells?
What is the main focus of T lymphocytes in the immune response?
What is the main focus of T lymphocytes in the immune response?
Which type of cells can monitor the presence of viral infection via uptake of apoptotic bodies of infected cells?
Which type of cells can monitor the presence of viral infection via uptake of apoptotic bodies of infected cells?
Which type of cells are used by the virus to enter organs through transcytosis?
Which type of cells are used by the virus to enter organs through transcytosis?
What is the main route for viral spread in the body?
What is the main route for viral spread in the body?
What is the difference between transplacental infection and perinatal infection?
What is the difference between transplacental infection and perinatal infection?
What determines the pattern of systemic illness during a viral infection?
What determines the pattern of systemic illness during a viral infection?
How do viruses like HPV access the body?
How do viruses like HPV access the body?
Which of the following is an example of direct transmission of a virus?
Which of the following is an example of direct transmission of a virus?
What is the role of neuraminidase in the entry of the influenza virus into the human body?
What is the role of neuraminidase in the entry of the influenza virus into the human body?
Which part of the body provides a large surface area for virus interaction, making it the most common portal of entry for viruses into the human body?
Which part of the body provides a large surface area for virus interaction, making it the most common portal of entry for viruses into the human body?
What is the function of mucus-secreting goblet cells in the respiratory tract?
What is the function of mucus-secreting goblet cells in the respiratory tract?
What must viruses entering via the gastrointestinal tract be resistant to in order to successfully survive and replicate in the immune cells?
What must viruses entering via the gastrointestinal tract be resistant to in order to successfully survive and replicate in the immune cells?
Which type of receptors recognize MAMPs and activate transcription factors to promote the expression of IFNs and inflammatory cytokines?
Which type of receptors recognize MAMPs and activate transcription factors to promote the expression of IFNs and inflammatory cytokines?
What is the function of cytoplasmic RNA helicase RIG-1 in the host immune response to viral infections?
What is the function of cytoplasmic RNA helicase RIG-1 in the host immune response to viral infections?
What is the main route for viral spread from one organism to another?
What is the main route for viral spread from one organism to another?
Which step is involved in the intrinsic immune response to a pathogen?
Which step is involved in the intrinsic immune response to a pathogen?
What type of immune response does the immune system mount in response to viral infections?
What type of immune response does the immune system mount in response to viral infections?
Viral pathogenesis refers to how a virus causes a ______
Viral pathogenesis refers to how a virus causes a ______
A strain of a certain virus is more ______ than another strain if it commonly produces more severe disease in a susceptible host
A strain of a certain virus is more ______ than another strain if it commonly produces more severe disease in a susceptible host
Viral shedding pertains to the shedding of infectious virus into the environment, which is the ______ stage in viral pathogenesis
Viral shedding pertains to the shedding of infectious virus into the environment, which is the ______ stage in viral pathogenesis
Viral shedding usually occurs from the body surfaces involved in viral entry and occurs at different stages of disease depending on the particular ______ involved
Viral shedding usually occurs from the body surfaces involved in viral entry and occurs at different stages of disease depending on the particular ______ involved
A virus is pathogenic for a particular host if it can infect and cause signs of ______ in that host
A virus is pathogenic for a particular host if it can infect and cause signs of ______ in that host
NK cells release enzymes that will induce a caspase signalling cascade and induce cell death to ______ cell
NK cells release enzymes that will induce a caspase signalling cascade and induce cell death to ______ cell
3 pathways activating complement system: classical, lactin, and alternative ______
3 pathways activating complement system: classical, lactin, and alternative ______
The Complement System is composed of serum proteins that form a cascade ultimately resulting in the enhancement of ______ response
The Complement System is composed of serum proteins that form a cascade ultimately resulting in the enhancement of ______ response
macrophages, dendritic cells) are ______
macrophages, dendritic cells) are ______
B lymphocytes - mediates humoral immunity; focuses on eradicating virus particles via ______, release antibodies
B lymphocytes - mediates humoral immunity; focuses on eradicating virus particles via ______, release antibodies
Direct transmission includes transfer of the virus by direct contact or droplet spread, with direct contact involving skin-to-skin contact, sexual intercourse, or kissing, and droplet spread involving the transmission of virions in respiratory ______.
Direct transmission includes transfer of the virus by direct contact or droplet spread, with direct contact involving skin-to-skin contact, sexual intercourse, or kissing, and droplet spread involving the transmission of virions in respiratory ______.
The respiratory tract is the most common portal of entry for viruses into the human body, with the mucosal surfaces providing a large surface area for virus ______.
The respiratory tract is the most common portal of entry for viruses into the human body, with the mucosal surfaces providing a large surface area for virus ______.
Influenza virus is an example of a virus that enters via the respiratory tract, developing ways to overcome the host’s defenses and utilizing neuraminidase to cleave sialic acid for ______.
Influenza virus is an example of a virus that enters via the respiratory tract, developing ways to overcome the host’s defenses and utilizing neuraminidase to cleave sialic acid for ______.
The upper respiratory tract contains abundant goblet cells that produce mucus, serving as a physical and chemical barrier and lined with cilia that move to push mucus and trapped contents to the ______.
The upper respiratory tract contains abundant goblet cells that produce mucus, serving as a physical and chemical barrier and lined with cilia that move to push mucus and trapped contents to the ______.
Viruses entering via the gastrointestinal tract must be resistant to the low pH, bile, and enzymes present in the hostile environment, with successful viruses being able to survive and replicate in the immune ______.
Viruses entering via the gastrointestinal tract must be resistant to the low pH, bile, and enzymes present in the hostile environment, with successful viruses being able to survive and replicate in the immune ______.
Host Immune Response and Viral Spread1. The immune system responds to viral infections through ______ (nonspecific) and Adaptive (specific) immune responses.
Host Immune Response and Viral Spread1. The immune system responds to viral infections through ______ (nonspecific) and Adaptive (specific) immune responses.
Intrinsic cell response to MAMPs involves recognition of specific macromolecules shared among microorganisms, such as dsRNA, peptidoglycan, LPS, and ______.
Intrinsic cell response to MAMPs involves recognition of specific macromolecules shared among microorganisms, such as dsRNA, peptidoglycan, LPS, and ______.
Protein kinase R (PKR) serves as a sensor for viral dsRNA and inhibits cap-dependent translation by ______.
Protein kinase R (PKR) serves as a sensor for viral dsRNA and inhibits cap-dependent translation by ______.
Host receptors, such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs), recognize MAMPs and activate transcription factors to promote the expression of ______ and inflammatory cytokines.
Host receptors, such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs), recognize MAMPs and activate transcription factors to promote the expression of ______ and inflammatory cytokines.
Viral spread occurs through Lytic and Lysogenic response during replication, with defense mechanisms inhibiting virus ______.
Viral spread occurs through Lytic and Lysogenic response during replication, with defense mechanisms inhibiting virus ______.
Viral spread in the body occurs via the bloodstream or ______ (viremia) and neural spread through neurons.
Viral spread in the body occurs via the bloodstream or ______ (viremia) and neural spread through neurons.
Many viruses produce disease at sites distant from their entry point by disseminating within the ______.
Many viruses produce disease at sites distant from their entry point by disseminating within the ______.
Capillary epithelial cells with sinusoids/fenestrations can be used by the virus to enter organs through ______ or replicate inside the cells.
Capillary epithelial cells with sinusoids/fenestrations can be used by the virus to enter organs through ______ or replicate inside the cells.
Congenital infections occur when a virus crosses the placenta during ______, leading to long-term virus persistence in the child.
Congenital infections occur when a virus crosses the placenta during ______, leading to long-term virus persistence in the child.
HIV is more likely transmitted in male-female than ______ sexual contact.
HIV is more likely transmitted in male-female than ______ sexual contact.
RIG1, MDA5, cGAS, TLR, TRIF, and Myd88 activate ______ and IRF which induce expression of interferons (type I)
RIG1, MDA5, cGAS, TLR, TRIF, and Myd88 activate ______ and IRF which induce expression of interferons (type I)
Interferons when transcribed and released, they bind to interferon receptors which induce transcription of ______; positive feedback
Interferons when transcribed and released, they bind to interferon receptors which induce transcription of ______; positive feedback
Once it recognizes dsRNA, PKR phosphorylates eiF2-GDP but not where it is supposed to be. This inhibits GDP to become GTP. This inhibits ______
Once it recognizes dsRNA, PKR phosphorylates eiF2-GDP but not where it is supposed to be. This inhibits GDP to become GTP. This inhibits ______
When interferons are released, they bind to IFNAR receptors which will activate ______ pathway
When interferons are released, they bind to IFNAR receptors which will activate ______ pathway
Jak and Tyk can autophosphorylate each other’s tyrosines. They phosphorylate and activate Stat protein which activates IRF. IRF binds to ISRE (IFN-sensitive response element) that will induce expression of more ______ or other genes like PKR
Jak and Tyk can autophosphorylate each other’s tyrosines. They phosphorylate and activate Stat protein which activates IRF. IRF binds to ISRE (IFN-sensitive response element) that will induce expression of more ______ or other genes like PKR
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Study Notes
Modes of Viral Transmission and Entry into the Human Body
- In some viral infections, such as rabies, humans represent dead-end infections, and shedding does not occur.
- Direct transmission includes transfer of the virus by direct contact or droplet spread, with direct contact involving skin-to-skin contact, sexual intercourse, or kissing, and droplet spread involving the transmission of virions in respiratory droplets.
- Indirect transmission involves the presence of an intermediary between hosts, including airborne transmission carried by dust or aerosolized particles and transmission via fomites or vectors such as mosquitoes and ticks.
- For host infection to occur, a virus must first attach to and enter cells of the body surfaces—skin, respiratory tract, gastrointestinal tract, or urogenital tract.
- The respiratory tract is the most common portal of entry for viruses into the human body, with the mucosal surfaces providing a large surface area for virus interaction.
- Influenza virus is an example of a virus that enters via the respiratory tract, developing ways to overcome the host’s defenses and utilizing neuraminidase to cleave sialic acid for entry.
- The upper respiratory tract contains abundant goblet cells that produce mucus, serving as a physical and chemical barrier and lined with cilia that move to push mucus and trapped contents to the throat.
- In the lower respiratory tract, smaller aerosolized particles or liquids can travel, with mucus-secreting goblet cells being less abundant and ciliated cells present at the beginning but absent in the alveoli of the lungs.
- The gastrointestinal tract, stretching from the mouth to the anus, contains fingerlike projections called villi, lymph node–like masses called Peyer’s patches, and specialized epithelial cells such as M cells and Paneth cells that play roles in immune surveillance and defense.
- Viruses entering via the gastrointestinal tract must be resistant to the low pH, bile, and enzymes present in the hostile environment, with successful viruses being able to survive and replicate in the immune cells.
- The host provides protection against viruses entering through the gastrointestinal tract, such as saliva containing enzymes and antibodies, stomach acid, and bile, which can break down and denature viruses.
- Acid-labile viruses are easily destroyed in acidic environments, while acid-resistant viruses contain capsid proteins that are not denatured by low pH. For example, Rhinoviruses are acid labile, whereas Poliovirus is acid resistant within the Picornaviridae family.
Host Immune Response and Viral Spread
- Rabies virus uses Diapedesis/Trojan Horse Approach to infect immune cells and enter the BBB.
- Directional release allows the virus to evade immune response by infecting neighboring cells and polarized release for epithelial cells.
- Viral spread occurs through Lytic and Lysogenic response during replication, with defense mechanisms inhibiting virus replication.
- The immune system responds to viral infections through Innate (nonspecific) and Adaptive (specific) immune responses.
- Viral spread from one organism to another occurs horizontally through various body fluids and shedding from infected body surfaces.
- Shedding of viruses occurs at different stages of the disease, representing the time when an infected individual is infectious to contacts.
- Environmental factors like humidity, temperature, and particle size affect viral transmission.
- Host receptors, such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs), recognize MAMPs and activate transcription factors to promote the expression of IFNs and inflammatory cytokines.
- Intrinsic immune response is the infected cell's response to a pathogen without relying on transcription, mediated by proteins that detect and eliminate pathogens or induce gene transcription.
- Intrinsic cell response to MAMPs involves recognition of specific macromolecules shared among microorganisms, such as dsRNA, peptidoglycan, LPS, and flagellin.
- Cytoplasmic RNA helicases RIG-1 and MDA5 function as RNA sensors, detecting specific types of viral RNA.
- Protein kinase R (PKR) serves as a sensor for viral dsRNA and inhibits cap-dependent translation by eIF2α.
Viral Entry and Spread in the Body
- Poliovirus, reovirus, and HIV exploit M cells for entry past the urogenital tract epithelium.
- Genital tract refers to reproductive organs; sexually transmitted diseases are transmitted via sexual activity.
- HIV is more likely transmitted in male-female than male-male sexual contact.
- Viruses like HPV infect genital epithelium, while hepatitis B virus and HIV access the body through breaks or cell receptor binding.
- The skin, composed of epidermis and dermis, serves as a barrier against virus entry; insect bites and animal bites can also introduce viruses.
- Congenital infections occur when a virus crosses the placenta during pregnancy, leading to long-term virus persistence in the child.
- Transplacental infection and perinatal infection are different; C-section minimizes perinatal infection, recommended for mothers with diseases like HIV.
- Viral tropism determines the pattern of systemic illness during an infection.
- Viral entry into different organs is determined by cell susceptibility, permissiveness, immune cells, and tissue accessibility.
- Many viruses produce disease at sites distant from their entry point by disseminating within the host.
- Viral spread in the body occurs via the bloodstream or lymphatics (viremia) and neural spread through neurons.
- Capillary epithelial cells with sinusoids/fenestrations can be used by the virus to enter organs through transcytosis or replicate inside the cells.
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